summary of ecg abnormalities

8/10/2019 Summary of ECG Abnormalities

1/7

15.12.2014 Summary of ECG Abnormalities

http://almostadoctor.co.uk/print/7 1/7

Published on almostadoctor - free medical student revision notes (http://almostadoctor.co.uk)

Home > Systems > The Cardiovascular System > ECGs > Summary of ECG Abnormalities

Summary of ECG Abnormalities

Abnormality ECG sign Seen in Pathology

Sinus rhythm regular p waves, andeach p wave is followedby a QRS. 60-100bpm

All leads (best tolook at the

rhythm strip)

None

Sinus Tachycardia Same as above, except>100bpm

All leads (best tolook at the

rhythm strip)

Does not represent cardiacpatholoy. May be a sign of anxiety,dehydration, recent exercise, orgeneral illness (e.g. sepsis,pneumonia, respiratory pathology,other illness)

Sinus bradycardia Same as above except


2/7


3/7



Complete (third degree)heart block

90 P waves/min, onlyabout 38 QRS/min, and

not relationshipbetween the P waves

and the QRScomplexes. QRS will

often have anabnormal shape, and

be broad (>120ms).

However, the P-Pintervals will be regular,as will the R-R intervals they are just not intime with each other.

The rhythm of theventricles is the escape

rhythm.

Best in II and V1 This is an AV node block.Atrialactivity will be completely normal,

but this conductivity does not passinto the ventricles.

This always indicates underlyingdisease the disease is oftenfibrosis rather than ischaemia, butit can occur in MI.

RBBB right bundlebranch block

ECG may appearnormal. In some people

there may be 2 Rwaves. This creates a

distinctive pattern:V1 there is an Mshaped QRS this issometimes called anRSR patternV6 there is a Wshaped QRSWide QRS (120ms)

These are infra-Hisian blocks. Inbundle branch blockages, the

wave of depolarisation can stillreach the IV septum, then the

PRinterval will be normal andit is. However, the time taken for

the depolarisation to spreadthroughout the ventricles islonger thus QRS complex

duration is lengthened.In the acute setting it may be

caused by MIRBBB may indicate right sideddisease. The two R waves indicate

the depolarisation of the right andleft sides of the heart at differenttimes (the right depolarises afterthe left).You can remember the patternwith the word MarroW there is Min V1, and W in v6, and the rr tellsyou it is on the right!There is NOT specific treatment,and it is often caused by an atrialseptal defect.In the acute setting it may be

caused by MILBBB often indicatesleft sidedheart disease. Remember thepattern with WillaM.Causes:

Aortic stenosis, dilatedcardiomyopathy, acute MI, CADSymptoms:Syncope, and in more severecases heart failure. Those withsyncope and / or heart failure

will usually be treated with apacemaker.

LBBB left bundlebranch block

V1 there is an Wshaped QRSV6 there is a Mshaped QRSWide QRS (>120ms)

The axis can bedeviated either way inBBBs, but it is mostcommonly normal

Sinus bradycardia Normal rhythm


4/7



immediately after MI

Sinus Tachycardia Normal rhythm>100bpm

Anywhere Associated with exercise, fear,pain, haemorrhage,

thyrotoxicosis

Supraventricularrhythms

This is any rhythmthat originates outside

the ventricle

Examples include:-

Sinus rhythms- LBBB- RBBB

Ventricular rhythms

(aka escape rhythms)Atrial escape

Junctional escape

Ventricular escape

Acceleratedidioventricular rhythm

Wide QRS complexes Anywhere

Abnormal p wave (e.g.inverted)

Normal QRSSome normal beats

after the abnormal one

Anywhere This occurs when the SA nodefails to depolarise. Instead,

some other part of the atriumdepolarises and sends the

signal to the ventricles.

No p wavesNormal QRS

Slightly slow rate (max75bpm)

The escape occurs somewhere atthe AV junction. It occurs when

the rate of depolarisation of the SAnode falls below the rate of the AVnode, thus the AV node starts the

beat instead. The resulting

bradycardia reduces cardiacoutput and can cause

symptoms similar to otherbradycardias such as:

-

Dizziness-

Light-headedness- Syncope- Hypotension

Usually the bradycardia can betolerated as long as it is above50bpm

Two types:-

Many p wavesper QRS(complete heartblock)

- Occasionalmissing p wave,followed by longgap, and then aventricular QRS,then normalrhythm

Somewhere along the line the pwaves isnt getting conducted to

the ventricles, and thus theventricles depolarise at their

normal escape rate.

Wide QRSRhythm of about

75bpmNo p waves

Abnormal T waves

Dont confuse this withventricular tachycardia which

requires a HR of >125pbm.Otherwise it looks very similar.

Usually benign and does notneed to be treated.Alsoassociated with MI

Extrasystoles(aka ectopics)

These are easy they are the same as ventricular escapes, except that wherein escapes the escape beat comes after a pause in the rhythm, in

extrasystole, there is an abnormal beat earlier than expected.The QRS complexes are the same as those of sinus rhythm, but there are

usually abnormal p waves that tend to come immediately before or immediatelyafter the QRS.

Inferior MI(probably the rightcoronary artery)

ST elevation II, III, aVF (theinferior leads)

The ST elevation in these leads isoften accompanied by ST

depression in the antero-lateralleads V1-V6, and possibly in
http://almostadoctor.co.uk/content/systems/neurology-psychiatry/psychiatry/depressionhttp://almostadoctor.co.uk/histories/dizziness-differentialshttp://almostadoctor.co.uk/content/systems/-cardiovascular-system/myocardial-infarction-and-acute-coronary-syndromes-acshttp://almostadoctor.co.uk/content/systems/-cardiovascular-system/myocardial-infarction-and-acute-coronary-syndromes-acshttp://almostadoctor.co.uk/content/systems/endocrinology/thyroid-gland/hyperthyroidism-thyrotoxicosishttp://almostadoctor.co.uk/content/systems/-cardiovascular-system/myocardial-infarction-and-acute-coronary-syndromes-acshttp://almostadoctor.co.uk/content/systems/neurology-psychiatry/neurology/falls


5/7



lead I and aVL

Anterior MI(probably the left

anterior descending)

ST elevation V2-5 theanterior leads

This will also cause deep qwaves. The presence of Q waves

implies a full thicknessinfarction.

Posterior MI ST depression, tall Rwaves

V1-V3 Posterior MI is unusual! Thechanges that occur are oppositeto the changes of other type ofMI. thus the tall R waves are the

opposite of Q waves (remember Qwaves are negative), and ST

depression occurs in place of STelevation

ST elevation MI(STEMI)

ST elevation >2mm in2+ chest leads OR

>1mm in 2+ limbleads,

T-wave inversion (afterseveral hours)

Pathological Q waves(24 hours +)

T waveinversion occurs

within a fewhours of MI,

pathological Qwaves occurseveral daysafter initial MI

Both factors, if they occur, areusually permanent. In a full

thickness infarction then thereare pathological Q waves, and Twave inversion, but in a non-fullthickness MIthen there is only T

wave inversion. Thedifferentiation between full

/thickness and non full thickness ispretty much the same as ST

elevation / non-ST elevationNSTEMI Pathological Q waves

only

Ventriculartachycardia

Wide QRS, no pwaves, T waves difficult

to identify, rate>200bpm

? Can be difficult to differentiatefrom BBB. BBB has p waves, and

a QRS generally 120-160ms. VT ismore likely scenario after MI, and

has QRS >160ms

Supraventriculartachycardia

Narrow QRS

Ventricular fibrillation No discernable

pattern, no QRS, no P,no T

Patient is very likely to lose

consciousness thus thediagnosis is easy!

Wolff-Parkinson-White SYndrome

Delta waves present,right axis deviation,

short PR interval, shortQRS

Accessory pathway, usually fromthe left atria to the left ventricleallows direct transition of thesignal, bypassing the AV node,hence the shortened PR interval. Ithas a risk of mortality as it cancause re-entry tachycardiahowever, most patients aresymptomless and live with noproblems.

The digoxin effect Depression of ST,inverted T waves

widespread This causes a sloping ST segmentthat has a reversed tick look. Thisoccurs because digoxin blocks the

na/K pump, which increasesintracellular Ca2+

concentrations. (similarly,ischaemia causes reduced

production of ATP, and thusreduced pump activity)

Pericarditis T wave inversion (rare:also ST elevation)

Widespread If ST elevation does occur, thenthe ST waves will appear saddle

shaped thus helping you todifferentiate it from MI. also, theelevation in MI tends to be

confined to a certain area, but inpericarditis, it is widespread

P pulmonale Tall ,peaked T waves, p Lead II Seen in cor pulmonale, or pretty
http://almostadoctor.co.uk/content/osces/year-3/examinations/pr-examhttp://almostadoctor.co.uk/content/systems/-cardiovascular-system/myocardial-infarction-and-acute-coronary-syndromes-acshttp://almostadoctor.co.uk/content/systems/-cardiovascular-system/myocardial-infarction-and-acute-coronary-syndromes-acshttp://almostadoctor.co.uk/content/systems/-cardiovascular-system/myocardial-infarction-and-acute-coronary-syndromes-acshttp://almostadoctor.co.uk/content/systems/-cardiovascular-system/heart-failurehttp://almostadoctor.co.uk/content/systems/-cardiovascular-system/myocardial-infarction-and-acute-coronary-syndromes-acshttp://almostadoctor.co.uk/content/systems/-cardiovascular-system/myocardial-infarction-and-acute-coronary-syndromes-acshttp://almostadoctor.co.uk/content/systems/-cardiovascular-system/myocardial-infarction-and-acute-coronary-syndromes-acshttp://almostadoctor.co.uk/content/systems/-cardiovascular-system/pericarditishttp://almostadoctor.co.uk/content/systems/-cardiovascular-system/drugs-affect-cardiovascular-system/digoxinhttp://almostadoctor.co.uk/content/systems/neurology-psychiatry/psychiatry/depressionhttp://almostadoctor.co.uk/content/systems/-cardiovascular-system/myocardial-infarction-and-acute-coronary-syndromes-acshttp://almostadoctor.co.uk/content/systems/-cardiovascular-system/myocardial-infarction-and-acute-coronary-syndromes-acshttp://almostadoctor.co.uk/content/systems/-cardiovascular-system/myocardial-infarction-and-acute-coronary-syndromes-acshttp://almostadoctor.co.uk/content/systems/-cardiovascular-system/drugs-affect-cardiovascular-system/digoxinhttp://almostadoctor.co.uk/content/systems/neurology-psychiatry/psychiatry/depressionhttp://almostadoctor.co.uk/content/systems/neurology-psychiatry/psychiatry/depressionhttp://almostadoctor.co.uk/content/systems/-cardiovascular-system/myocardial-infarction-and-acute-coronary-syndromes-acshttp://almostadoctor.co.uk/content/osces/year-3/examinations/pr-examhttp://almostadoctor.co.uk/content/systems/-cardiovascular-system/pericarditishttp://almostadoctor.co.uk/content/systems/-cardiovascular-system/myocardial-infarction-and-acute-coronary-syndromes-acs


6/7



wave height >2mm inlead II

much anything that causes rightatrial enlargement (or

hypertrophy) such as tricuspidstenosis or pulmonary

hypertension

Bifid P waves (P-Mitrale)

P waves with twopeaks, broad lookslike an M hence the

name Mitrale

? Left ventricular hypertrophy

Bi-phasic T waves T waves with t peaks Can occur as a result of MIProlonged QT interval Prolonged QT The corrected QT, is the QT

interval as it would be at 60bpm. ifthis is long, then there is a risk ofsudden cardiac death. It can be

congenital, but also caused bydrugs

Hyperkalaemia Wide, tall, tented Twaves,

shortened/absent STsegment, small or

absent p waves, wideQRS

? Can lead to VF and AF

Left ventricularhypertrophy

S wave in V1 or V2 >35mm AND R wave in V5 or V6>35mm R in aVF >20mmR in aVL>11mm

Any chest lead >45mmR in lead I>12mm

Pacemaker Occasional P waves,not related to QRS,

QRS precede by largespike, QRS complexesbroad

? The large spike is pacemakerstimulus. The QRSs are wide

because the stimulus originates inthe ventricles

Axis deviation

Lead I Lead II Axis

+ + Normal

+ - LAD

- Either RADaVR should always be negative!If it is positive,it is called north-west axis. it could be due to incorrect limb lead placement,dextrocardia, or artificial pacing, due to the pacemaker wire - this enters the heart at the apex.Carotid sinus pressureBy applying pressure to the carotid sinus you can stimulate the AV and SA nodes via vagalstimulation. This will reduce the frequency of discharge of the SA node, and increase the time ofconduction across the AV node.Thus, by applying pressure to the carotid sinus you can:

Reduce the rate of some arrhythmias

Completely stop some arrhythmiasIt will have NO EFFECT ON VENTRICULAR TACHYCARDIAS thus is can help youdifferentiate.

Applying the pressure basically reduces the frequency of QRS complexes, and allows the
http://almostadoctor.co.uk/content/systems/-cardiovascular-system/myocardial-infarction-and-acute-coronary-syndromes-acshttp://almostadoctor.co.uk/content/systems/-cardiovascular-system/hypertension/pathologyhttp://almostadoctor.co.uk/content/systems/-cardiovascular-system/atrial-fibrillationhttp://almostadoctor.co.uk/content/systems/nephrology/potassium


7/7



underlying atrial arrhythmia to become more visible.Copyright 2009 - 2013 - Dr Tom Leach

Source URL (modified on 10/09/2014 - 04:06): http://almostadoctor.co.uk/content/sy stems/-cardiovascular-system/ecgs/summary-ecg-abnormalities

summary of ecg abnormalities

Documents